The invention relates to a turbocompressor.
A turbocompressor is known which comprises a radial turbocompressor and an electric motor, with each of these units being arranged in a separate housing and with the shaft of the electric motor being coupled to the shaft of the radial turbocompressor via a flexible shaft part.
Disadvantageous in this known turbocompressor is the fact that the latter is designed to be rather large, that a plurality of seals and bearings is required and that the manufacturing costs of the turbocompressor are therefore relatively high.
The document DE 27 29 486 C 1 discloses in FIG. 1a a turbocompressor which includes two two-stage radial turbocompressors and also an electric motor, with these being coupled to a rigid shaft which is journalled at three positions with magnetic radial bearings. This embodiment has the disadvantage that the assembly is very complicated and difficult, that this arrangement is suitable for an at most two-stage radial turbocompressor and that the turbocompressor has relatively high dissipation losses.
It is an object of the present invention to propose an economically more advantageous turbocompressor.
This object is attained with a turbocompressor comprising an electric motor, a multistage radial turbocompressor and also a common shaft, with a part section of the shaft being formed as the armature of the electric motor and wherein a further part section of the shaft is formed as the rotor of the radial turbocompressor, with the rotor including a compressor shaft and also compressor wheels connected therewith, wherein a plurality of magnetic radial bearings are arranged spaced apart in the direction of extent of the shaft for the journalling of the shaft, wherein a single electromagnetic radial bearing is arranged between the armature of the electric motor and the compressor wheel, and wherein the electric motor, the radial turbocompressor, the shaft and also the radial bearings are arranged in a common housing sealed in gas-tight manner relative to the outside. The housing consists of a plurality of part housings which can be fixedly connected together, the electric motor is arranged in one part housing and the radial turbocompressor in one part housing and the armature of the electric motor and also the rotor of the radial turbocompressor are connectable to form a common shaft via a coupling arranged between the armature of the electric motor and the compressor wheel.
The object is furthermore satisfied in particular by a turbocompressor comprising an electric motor, a multiple-stage radial turbocompressor and a common shaft, with a partial section of the shaft being designed as the armature of the electric motor, and with a further partial section of the shaft being designed as the rotor of the radial turbocompressor, with the latter rotor comprising a compressor shaft and compressor wheels or impellers which are connected thereto, and with a plurality of electromagnetic radial bearings being arranged with spacing in the longitudinal direction of the shaft, with the radial bearings being supported on a common base element.
The object is further satisfied by a turbocompressor comprising a housing which is gas-tight towards the outside and within which an electric motor and also a multistage radial turbocompressor are arranged on a common shaft, wherein, for the journalling of the shaft, electromagnetic radial bearings are arranged spaced apart in its direction of extent and wherein a dry gas seal surrounding the shaft is provided between the electric motor and the radial turbocompressor in order to seal off the electric motor relative to the radial turbocompressor, with the electric motor having an inner space which is connected in fluid-conducting manner with an outlet opening which passes through the housing.
FIG. 1 shows a known turbocompressor which comprises an electric motor which is journalled at both ends and a radial turbocompressor which is journalled at both ends, with the shaft of the electric motor being coupled via a flexible shaft part to the shaft of the radial turbocompressor.
An advantage of the turbocompressor in accordance with the invention is to be seen in that for the complete journalling of the entire shaft, in comparison with the exemplary embodiment in accordance with FIG. 1, three radial bearings, preferably designed as electromagnetic radial bearings, suffice in that a single radial bearing is arranged between the electric motor and the compressor. The turbocompressor can thus be manufactured economically.
The entire shaft can be designed as a single piece. In an advantageous embodiment the shaft of the electric motor as well as the shaft of the radial turbocompressor are connected via a coupling, in particular a coupling with as high a stiffness as possible. A very stiff coupling permits the design of a total shaft which has a largely homogeneous stiffness in the longitudinal direction of the shaft. The entire shaft or, respectively, the entire rotatable components of the turbocompressor behave thereby like a compact shaft, which has a positive effect on a stable running behavior of the turbocompressor. In addition this enables the entire shaft to be journalled in the axial direction with the help of a single axial bearing. In the embodiment known from FIG. 1 a separate axial bearing each is required for the electric motor and the radial turbocompressor.
If a radial turbocompressor is arranged only at one side of the electric motor, then three radial bearings which are arranged to be spaced in the longitudinal direction of the shaft suffice for the complete journalling of the entire shaft. If a radial turbocompressor is arranged at each side of the electric motor, then four electromagnetic radial bearings which are arranged to be spaced in the longitudinal direction of the shaft suffice for the complete journalling of the entire shaft.
Dispensing with a radial bearing between the electric motor and the radial turbocompressor has in addition the advantage that the entire shaft can be shorter, which is rotor-dynamically advantageous, enables the forming of a lighter shaft, and yields a more compact construction of the turbocompressor in addition. In this it should be considered that electromagnetic radial bearings have a substantially lower bearing load in comparison with hydrodynamic radial bearings, which results in a more advantageous dynamic behavior of the rotor because of the shorter shaft as well as the lower weight, which are of decisive importance in order to operate the turbocompressor reliably and without disturbance by means of electromagnetic bearings. This aspect is in particular of importance for radial turbocompressors which compress a fluid to a high pressure of for example 600 bar. When such a highly compressed fluid encounters a flow disturbance, relatively large radial and axial forces are generated which can be absorbed by the electromagnetic bearing, which has only a limited load capacity, only when the dynamic behavior of the rotor of the entire system is optimized.
In a particularly advantageous embodiment the motor and the radial turbocompressor are arranged in a common, hermetically sealed-off housing, in particular in a pressure housing, with a fluid-conducting input and output line passing through the housing or being flanged onto the housing in order to conduct in and out the fluid to be compressed. This arrangement has the decisive advantage that no seals against the outside, in particular against the atmosphere, are required at the shaft, which in addition to the cost advantage yields the further advantages that periods of disuse which are caused by sealing problems no longer arise, and that the total length of the shaft can additionally be reduced, which again increases the total weight of the shaft and the stability of the shaft which is held by electromagnetic bearings.
The radial turbocompressor with a pressure housing which is hermetically sealed off against the outside also permits the motor-compressor plant in accordance with the invention to be operated at sites which were previously unsuitable for the operation of a radial turbocompressor, for example under water or in an environment with high pollutant content, a high degree of contamination or a high risk of explosion.
A further advantage of the turbocompressor in accordance with the invention is to be seen in that the latter can also be operated very reliably by remote control. The turbocompressor has for example no elaborate oil system for journalling the armature. In addition no or only few seals are required. The turbocompressor therefore has no components, for the operation of which an expert is required on site, or components which require a regular checking at relatively short time intervals. A start and stop process of the turbocompressor can be run by remote control, with it being possible to remotely monitor the states of the turbocompressor by means of sensors; and suitable measures, for example a stopping, can automatically be initiated when an irregularity is detected. A turbocompressor in the embodiment with a hermetically sealed-off pressure housing has the further advantage that the risk of disturbing influences acting from the outside is very low.
In order to compress the fluid to a high final pressure it was previously required to provide the turbocompressor with very expensive dry gas seals, with these dry gas seals having in addition to the high price the further disadvantage that they require a considerable maintenance and in addition represent a risk component, considering that most of the unpredictable periods of disuse of a turbocompressor are caused by damages to the dry gas seal.
In a further advantageous embodiment a portion of the compressed fluid or process gas respectively is used for the longitudinal gas cooling of the motor and the radial bearings. This is in particular advantageous in the use of a common, hermetically sealed-off pressure housing. A motor which is designed for suction pressure or standstill pressure is preferably used in this as the electric motor. In a further advantageous embodiment the electric motor has its own coolant circuit, which is separate from the radial turbocompressor.
In an advantageous embodiment of the turbocompressor in accordance with the invention the latter has a common base element which is for example designed in the shape of a plate and on which some, preferably all, radial bearings are supported. The arrangement of the radial bearings on a common base element has the advantage that the former are oriented in a definite position with respect to one another, and that the mutual displacements of the radial bearings which are caused by tension, compression or shear stresses or by temperature influences respectively can be kept to a minimum. A mutually precisely arranged orientation of the radial bearings is thus ensured at the most varied operating conditions. Advantageously, not only the radial bearings, but also the other elements, such as the electric motor, the radial turbocompressor, etc., are arranged on the base element. This enables an assembly of the turbocompressor as a finished total module at the manufacturing plant, also thanks not least to the compact construction of the turbocompressor in accordance with the invention. This module can be put into operation at the site of the application very rapidly since it is no longer necessary to precisely anchor the radial turbocompressor and the electric motor separately to a base and in so doing to set their mutual position precisely. In an advantageous embodiment the turbocompressor is arranged inside a housing, with a part of the housing, for example the inner wall of the housing which is arranged below, also forming the common base element at the same time.
In an advantageous embodiment of the turbocompressor the radial turbocompressor and the motor are arranged in a common housing, with the housing consisting of a plurality of partial housings which can be connected to one another, or of a substantially single housing. Advantageously, the entire drive apparatus is arranged in one partial housing and the entire radial turbocompressor in a further partial housing, with these partial housings preferably being designed to be mutually matched in such a manner that they can be directly centered and mutually firmly connected. In an advantageous embodiment the common housing is stiffly designed such that the entire turbocompressor, comprising the radial turbocompressor, the motor, etc., is mutually journalled substantially without displacement by the common housing so that the common housing, for example, is designed as a tube without external support or is designed to be supportable with only one to two supports on a base. This arrangement has the advantage that the possibility of stationary and/or non-stationary displacements of the bearing locations are to the greatest extent prevented, for which reason a setting of the bearings on site is omitted, so that the manufacture and the putting into operation of the turbocompressor takes place more economically. If in the common housing a slight dislocation of the individual shafts or, respectively, of the statically arranged parts of the motor or of the radial turbocompressor should nevertheless take place in the common housing, then there is also the possibility of compensating this deviation thanks to the use of electromagnetic radial bearings.
The known turbocompressor shown in FIG. 1 consists of a separate motor with its own housing and of a radial turbocompressor with a further, own housing. In this known arrangement the mutual movement of the housings or, respectively, the displacement of the individual shafts represents a considerable problem, which is caused by each housing being individually anchored at the base. Through different thermal expansions or other forces acting on the individual housings their position is changed. The arrangement in accordance with the invention of a motor and a radial turbocompressor on a common base element, in particular in a common housing, has the advantage that the base element or the housing respectively forms the reference for the journalling and therefore a mutual variation of the position of motor and radial turbocompressor is largely excluded.
The turbocompressor comprising a plurality of part housings has the advantages:
that the assembly of the full turbocompressor is very simple,
that one rotatable unit which can be separately balanced and weighted is arranged in each part housing,
that each part housing with the rotatable unit located therein can also be obtained from different suppliers; especially the electric motor and the radial turbocompressor can be obtained from different suppliers,
that the maintenance of the turbocompressor is simpler and more cost favorable.